Disposable cartridge for investigating physical properties of blood

ABSTRACT

A disposable cartridge for measuring the physical properties of blood is disclosed. A waste compartment supports a platform having first and second syringe fittings. First and second syringes containing blood samples to be measured are positioned within the fittings. At least one testing station is located on the platform for subjecting blood flowing from one of the syringes to a test station, and the testing station is connected at a second end to the waste compartment. Tests on blood running through each of the blood channels may be conducted by inducing various platelet activation conditions, such as piercing a channel, or putting a platelet activating substance within a test channel. The cartridge interfaces with a test stand which will measure pressure changes within each of the test channels.

The present invention relates to disposable devices for makingmeasurements of the physical properties of blood. Specifically, acartridge has been designed which is especially useful in conductingexperiments on native, non-anticoagulated blood.

In the treatment of various blood disorders, it has been necessary tomake measurements on whole, native blood to assess the formation ofplatelets and the adequacy of haemostatic functions of the blood beforeembarking on specific medical procedures for patients having thesedisorders. Further, other disorders such as myocardial infarction,stroke, thrombolysis or blood dissolution properties, must be monitoredand assessed repeatedly following recovery to prevent recurrence of ablood clot.

Techniques for measuring the physical attributes of platelet activation,all of which is related to the foregoing disorders, have been thesubject of numerous investigations. The difficulty in making suchmeasurements lies in the difficulty to collect native whole blood whichhas not been anticoagulated and conduct experiments which do not induceany platelet activation except under very controlled circumstances. Ininvestigating the behavior of native whole blood, a device forperforming in vitro haemostasis on native whole blood, is described inEPO Application No. 129425. This patent describes a laboratory techniquewhich is capable of simulating bleeding. A fresh supply of native bloodis connected to a polyethylene tube. A flow of blood is started throughthe tube and bleeding is simulated by establishing a hole in the tubingof a known diameter. The bleeding which occurs through the hole ismonitored, both optically and through a pressure measurement of the flowof blood.

A further improvement of this technique is described in a laterInternational Patent Application PCT/GB87/00633, having an internationalfiling date of Sep. 10, 1987. In this patent, multiple channels of bloodflow were established, and concurrent measurements of haemostasis weremade in each of the blood flow channels. This permitted a controlchannel having blood drawn at the same time, thus having substantiallythe same chemical composition to be measured and compared to each other.

The laboratory technique set forth in the above-referenced patentdocuments requires a fairly high level of skill on the part of thepersonnel conducting such tests. Further, as blood is known to carryviruses, including the deadly HIV virus, it is necessary that personnelalways take precautions to avoid contact with the blood.

A disposable blood-handling cassette is described in U.S. Pat. No.5,047,211 which will permit such tests to be carried on in accordancewith the preceding patent documents, while isolating medical personnelfrom coming in contact with the blood under test. The device, which iscompletely self-contained, includes multiple reservoirs which receive ablood sample for carrying out the experiments and investigation ofblood, as set forth in the previously identified patent documents.

Further investigation of these techniques have demonstrated how thehandling of blood, even in a disposable cartridge can result in plateletactivation before any testing begins. The process of extracting bloodfrom a human donor in itself can activate platelets which interfere withthe investigation of blood under controlled conditions.

It has also been found that further control over punching holes in ablood-carrying tubing is necessary in order to provide for repeatabilitybetween tests of succeeding samples of blood.

SUMMARY OF THE INVENTION

It is an object of this invention to provide for a disposable cartridgewhich can be used to carry out tests on blood.

It is a more specific object of this invention to provide for adisposable cassette which may be used in haemostasis and thrombolysismeasurements, and which effectively isolates infected blood samples fromusers of these devices.

It is yet a more specific object of this invention to provide a devicewhich is designed to avoid inadvertent platelet activation in a sampleof blood under test.

These and other objects of the invention are provided by a disposablecartridge which is capable of conducting tests on whole blood. Thecartridge is designed to introduce a minimum amount of disturbance tothe blood's physical properties, and specifically to avoid plateletactivation through handling of the blood samples. The cartridge createsan in vitro environment which models the circulatory system with regardto temperature and flow. In doing so, shear force experienced by theblood is accurately controlled. In this way, platelet activation ismaintained under control until tests are performed on the blood. Thedevice therefore permits the simulation of normal circulatory bloodconditions, as well as simulating a disease environment or injury duringtesting.

In carrying out the invention, the disposable cartridge incorporates atotally isolated compartment for tested blood which will preclude anyinadvertent contact with medical personnel. The compartment supports aplatform which includes at least one receptacle for receiving a bloodsample vessel such as a syringe. The use of the syringe as the blood.Iadd.sample .Iaddend.vessel avoids the platelet activation which occurswhen transferring the blood from a syringe used to draw the blood fromthe human donor to a reservoir in another test device. Further, thesyringe which acts as a blood sample vessel is exposed to a heatingplate of a test stand for maintaining the blood sample vessel at aconstant temperature, which improves the control over experiments beingconducted.

In accordance with the preferred embodiment of the invention,experiments are conducted with two blood samples contained in twosyringes. The first blood sample is used in a test channel to simulatebleeding. The second blood sample is used in a second test channel tosimulate the effect of a platelet-activating substance contained in thetest channel of the two-channel device on blood flowing through the testchannel.

The first of the channels provides for a flow of blood through apunching station, which forms an accurately-defined opening in the bloodtube to simulate bleeding. A pressure chamber is provided which containsa volume of immiscible fluid. Blood exiting the test channel enters itsown pressure chamber where it displaces the volume of immiscible fluidthrough an orifice into a waste compartment. A test stand associatedwith the disposable cartridge, provides a fluidic connection between thepressure chamber and a pressure transducer. As blood flows through thetest channel, the immiscible fluid is displaced through an orificegenerating pressure within the pressure chamber. Changes in measuredpressure will provide an accurate monitoring of platelet activity. Inaccordance with the preferred embodiment of the invention, the bleedingchamber is filled with a saline solution. Drops of blood exiting thepunctured opening in the channel having a punching station can beobserved in the tapered end of the bleeding chamber via an opticaldetecting device.

The second test channel provides for a second flow of blood from asecond syringe past a platelet-activating substance, into a secondpressure chamber. The second pressure chamber includes a volume ofimmiscible fluid which is displaced through orifice into the wastecompartment. A second transducer measures the changes in pressure withinthe pressure chamber as a measure of the platelet activity.

DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a test stand having a disposable cartridge inaccordance with the preferred embodiment of the invention for measuringthe physical properties of blood.

FIG. 2 illustrates a fluidic diagram of the first test channel providedby the cartridge and test stand of FIG. 1.

FIG. 3 is a fluidic diagram of a second test channel provided in thedisposable cartridge and test stand arrangement of FIG. 1.

FIG. 4 is a first section view of the cartridge inserted in the teststand.

FIG. 5 is a top section view of the disposable cartridge of FIG. 4.

FIG. 6 illustrates a second, section view of the cartridge illustratingthe pressure chambers which terminate each test channel.

FIG. 7 illustrates another section view of the punching station whichpierces a precise hole in one of the test channels.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, there is shown a disposable cartridge 11 inaccordance with a preferred embodiment of the invention, which isreceived within a test stand 10. The cartridge 11 supports a pair ofsyringes 20, which contains native, non-anticoagulated blood obtainedfrom a donor. The cartridge 11 will provide for a two-channel testdevice for measuring the properties of blood flowing from each of thesyringes 20 into first and second test channels which terminate in awaste compartment. The cartridge 11 is completely disposable andincludes two fittings for receiving each of the ends of syringes 20. Theassembly of the cartridge 11 and syringes 20, having two samples ofblood from which measurements of certain physical conditions of theblood are to be made, are inserted into the test stand 10 during theperformance of tests on the samples of blood.

The test stand 10 includes a support . .13.!. which is used to positionthe cartridge 11 with respect to the test stand 10. The support . .13.!.is driven by a stepping motor 17 to move the cartridge 11 against theheaters 21 and 29 of the test stand 10.

The test stand 10 supports two heaters 21 and 29. Heater . .1.!..Iadd.21 .Iaddend.will maintain each of the syringes 20 at a preferredtemperature to keep test conditions constant for all blood samples beingmeasured. The second heater 29 will maintain the two test channels ofthe cartridge 11 carrying the blood under test substantially equal tothat of the syringes 20.

The cartridge 11 is arranged in accordance with the principles set forthin the aforesaid patent documents so that an immiscible displacing fluidis introduced into the syringes 20, displacing the blood through thetest channels. The displacing immiscible fluid is supplied from a pairof reservoirs which are pressurized with air and received through sealedcoupling in the cartridge 11. Another pair of sealed couplings areconnected to a pair of conduits for supplying a displacing fluid fromanother reservoir to each pressure chamber which terminates the twoblood channels. Following filling of the pressure chambers withimmiscible fluid, a pair of pressure transducers connected to the pairof conduits monitor pressure changes in each blood channel. Changes inflow due to test conditions in each channel result in a pressure changewhich can be accurately monitored.

The plungers on the syringes 20 are maintained in position duringpressurization of the syringes 20 with the immiscible fluid by aretainer 23 which is connected to a linear actuator 25. Control overlinear actuator 25 will lower the retainer 23 to maintain the plungersof each of the syringes 20 in their unpressurized position. As the sizeof the blood sample may change, it is necessary to have the retainer 23adjustable to accommodate different plunger heights.

In accordance with the principles set forth in the devices and processesdescribed in the aforesaid patent documents, a support 30, supporting anoptical detector 28, is also provided. The optical detector 28 detectsblood which flows in a bleeding chamber during a test conducted in oneof the blood channels.

The two test channels which are provided by the system of FIG. 1, areschematically illustrated in FIGS. 2 and 3. FIGS. 2 and 3 illustrate thefluid circuits which are provided by each of the test channels in thecartridge device. FIG. 2 illustrates a test channel wherein the processof platelet activation is monitored by puncturing a blood-carryingchannel 40 with a punching needle assembly 43. The punching needleassembly 43 includes a guide and needle which, when driven by the linearactuator 45, will pierce a pair of precisely-positioned holes across acommon diameter in the blood carrying channel 40, at a controlled rate.

The blood-carrying channel 40 is connected to the receptacle 36 forreceiving the end of the syringe 20. The receptacle 36 also includes astandpipe section 38 which is connected to receive, through the sealedcoupling member 37, a supply of immiscible displacing fluid.

The blood channel 40 terminates in a pressure chamber 51. The pressurechamber 51 also receives a volume of immiscible displacing fluid from asecond sealed coupling member 54, connected to another source ofdisplacing fluid.

Initialization of the test channel requires that air pressure from pump33 be forced through air regulators 34 and 57 to a pair of oil supplies32 and 56.

The pressure chamber 51 is filled and air expelled via an orifice as theoil supply enters from valve 55 through the sealed coupling member 54 ofthe cartridge. The orifice is provided by the tube 53 which is connectedat one end to the domed pressure chamber 51 and at the other end to thewaste compartment 63.

As the volume of immiscible fluid is filling the pressure chamber 51, asimilar column of displacing fluid is entering through the flowregulator 35 and cartridge sealed coupling member 37. The standpipe 38is connected through the receptacle 36 to the sealed coupling member 37,and permits the immiscible oil to enter the syringe. The oil displacesthe blood through the proximal end 44 of blood channel 40.

Blood which flows through the channel 40 displaces the volume ofimmiscible fluid contained in the pressure chamber 51 through theorifice established by the tube 53, and into the waste compartment 63.The flow of blood thus established from the syringe 20 through channel40 represents an in vitro normal circulatory condition for the blood.Platelet activation is minimized until the punching operation commenceswhich will simulate bleeding, resulting in a state of high shear ratecausing platelet activation.

Prior to operating the linear actuator 45 which drives the punchingmechanism 43, a saline solution is pumped from a supply 48, via pump 47,through a coupling 50 into the bleeding chamber 42. The saline solutionwhich is heated in heater 46 fills the tapered portion of bleedingchamber 42 and washes the exiting blood from the hole punched in theblood-carrying channel 40. Care is taken to maintain and regulate thetemperature of the saline solution constant.

The tapered portion of the bleeding chamber 42 is observable by theoptical detectors 28. As is set forth in the foregoing patent documents,the duration of bleeding is detected by optical detector 28.

Once the pressure chamber 51 has been filled with the volume ofimmiscible fluid, the valve 55 is closed, isolating the source ofimmiscible fluid from the pressure chamber 51, leaving coupling member54 pressure transducer . .0.!. .Iadd.60 .Iaddend.connected to thepressure chamber 51. The pressure in this hydraulic circuit formed fromthe syringe 20, blood-carrying channel 40 and pressure chamber 51 willbe monitored and various changes in the physical characteristics ofblood can be monitored by the pressure transducer 60. Chief among thesechanges includes platelet aggregation which results from shear forces onthe blood exiting the punched hole in the channel 40. Initially, bloodexiting the holes will be detected in a lowering of the pressuremonitored by pressure transducer 60. Further, an optical signal will beproduced as blood flows into the bleeding chamber 42. As the plateletsaggregate in the hole, the resulting pressure changes will be monitoredby the transducer 60. This change in pressure occurring during thepunching of the holes, as well as the subsequent coagulation whichoccurs in the lumen of the tubes, will give the clinician significantdata regarding the condition of the blood under test.

The second channel provided by the disposable cartridge is shown in FIG.3. Identical components for this second test channel are marked with theidentical reference numerals. The test channel of FIG. 3 does notinclude a punching station for piercing the blood-carrying tube 40. Thischannel can suffice as a control channel and pressure changes noted bythe transducer 60 are accurately compared with the pressure transducer60 of FIG. 2.

Additionally, a platelet-inducing substance 61 may be introduced intothe channel 40 of FIG. 3, and the downstream pressure measured via thepressure transducer 60. This platelet-forming substance 61 may be acollagen substance, as described more particularly in the aforesaidinternational patent application. Platelet activation occurring from thesubstance 61 will result in a change in pressure for the test channel.These events may be accurately monitored by the pressure transducer 60,giving the clinician an opportunity to compare pressure changes fordifferent samples of blood in different tests. The second test channelcan also provide information to interpret the data obtained from thefirst channel. The initialization of the test channel is the same asthat of FIG. 2, wherein the pressure chamber 51 receives a volume ofimmiscible fluid, while the syringe 20 receives, through standpipe 38, asimilar volume of immiscible fluid.

In both devices, the outlet tubes 53 for the pressure chambers areconnected to the waste compartment and displaced immiscible fluid entersthe waste compartment and is securely maintained within the cartridge.The displacement of the immiscible fluid through the orifice created bythe outlet tubes 53 creates a pressure which is monitored by thepressure transducer 60. Thus, flow conditions are accurately monitoredas long as the flow through the orifice continues. It should be notedthat the punched holes in tube 40 of the first channel will reduce theflow into pressure chamber 51, dropping the monitored pressure. When theblood totally clots, pressure drops to zero since there is no flow. Theoptical monitoring provided by optical detector 28 will detect anyexpulsion of a platelet plug from the punched holes. At the conclusionof the tests, the entire cartridge with connected syringes may bedisposed of safely.

Having generally described the tests carried out by the test stand 10and disposable cartridge 11, a more detailed description of thedisposable cartridge will now be made.

Referring now to FIG. 4, there is shown a partial section view of thecartridge 11, as viewed from the test stand which receives the cartridge11. The cartridge 11 includes a waste compartment 63 supporting on thetop surface thereof a platform 62. Those components shown in FIG. 4 canbe made of a plastic material through injection molding or similarprocesses.

The platform 62 supports a pair of studs 24, each of which receives theflared ends of the syringe receptacles 36. The studs 24 support thestandpipes 38 which are coaxial with the axis of the receptacles.Iadd.or hydraulic couplings .Iaddend.36. The end of the receptacles 36which receives the front tip 22 of each of the syringes 20 has a luerfitting taper to provide a force fit, tight against any blood orpressurizing fluid leakage.

The stud 24 for each of the test channels includes a . .fluidic.!..Iadd.factor .Iaddend.coupling member 37, which may be an elastomericsubstance which is pierced by an injection needle or pointed cannulafrom the test stand 10. Displacing fluid is received through thecoupling member 37 and supplies the immiscible displacing fluid throughthe standpipes 38 into the body of the syringes 20.

Each of the pressure chambers 51 extends through the platform and havedomed portions 69 which are connected to the outlet tubes 53 whichprovide an orifice. Displacing fluid for the pressure chambers 51 isreceived through the couplings 54, which also may be of an elastomericinsert, pierced by a needle or pointed cannula supplying the displacingfluid. A similar fluid coupling is provided at 50 for injecting a salinesolution into the bleeding chamber 42.

Each of the blood-carrying tubes 40 for each test channel is supportedon a surface 39. Surface 39 is positioned so that in use it touches theheater 29, thereby maintaining constant the temperature of theblood-carrying tubes 40. The receptacles 36 and studs 24 are alsopositioned such that each of the syringe bodies 20 is located within theheater 21.

The blood carrying tubes 40 have a routing path which is initiallystraight down, and then routed upward. A collagen substance 61 is shownintroduced in one of the blood carrying tubes which is by the radius ofthe blood carrying tube.

A top cover 67 is fixed to the platform . .64.!. .Iadd.62 .Iaddend.andincludes a pair of guide holes .Iadd.20 .Iaddend.which support thesyringes 20 in alignment with the receptacles .Iadd.or hydrauliccouplings .Iaddend.36. .Iadd.Guides 70 position the syringes tangentialto the rear edge of the cartridge so that the syringes can be locatedagainst a common heating surface. .Iaddend.The cover 67 also includes ahole 66 which receives the ram 68. Ram 68 is advanced by the linearactuator 45 towards the punching mechanism 43 at a controlled speed tocontrol the shape of the hole being formed.

The section view of FIG. 5 illustrates the test channels. The testchannels include the bleeding chamber 42, as well as theplatelet-activating substance 61. Also shown is an outlet 72 for thesaline solution which enters via the coupling 50 to fill the bleedingchamber 42.

Details of the cartridge punching station 43 are shown more particularlyin FIGS. 6 and 7. The punching station includes a plunger 80 whichslides within a sleeve 77. A guide 75 having a forked end positionedover the blood-carrying tube 40 is connected to the sleeve 77. Acentrally-located needle 76 is connected to move with the plunger 80when the ram . .62.!. .Iadd.68 .Iaddend.is accelerated against thesurface 83. The end of the needle 76 is located within a through-hole inthe forked end. The forked end positions the needle tip in line with theinner diameter of the blood-carrying tube 40.

The plunger 80 moves inside the sleeve 77, pushing the needle throughthe hole in the guide 75, and pierces opposite sides of theblood-carrying tube. A detent on the plunger 80 moves between a firstnotch 79 and second notch 81 in the sleeve 77. As the ram 82 pushesplunger 80 against the force of a spring 82 when the ram is retracted,the spring 82 withdraws the plunger 80, the needle 76 and guide 75. Theresult is a pair of holes in the blood-carrying tube 40, which permitsbleeding to occur in the bleeding chamber 42. The elastomeric material83 at the top of the plunger seals the cartridge against leakage.

The blood profusing from the hole drains via the tapered section 71 withthe saline solution into the waste compartment 63, where it is captured.Other waste material from the pressure chambers 51 also exit via thedrain tubes 53 to the waste compartment 63. The level of saline in thebleeding chamber 42 is controlled by the rate at which saline isintroduced, and the height of the exit port 73. The level of saline ismaintained at a level which insures washing of the holes punched in theblood-carrying tubes.

The foregoing structure of the cartridge provides for a minimumdisturbance to blood samples which are to be tested under verycontrolled test conditions. By using the syringes as the reservoir, theinadvertent activation of platelets in the test sample are kept to aminimum. Further, the entire cartridge is designed such that the bloodsample throughout the test channel can be maintained at a constanttemperature, thus minimizing the effects of temperature differentials oneach test being conducted. Once the test is completed, the motor 17 ofFIG. 1 can be reversed and by grasping the handle 74 of the cartridge,the entire cartridge with connected syringes may be disposed of withoutrisk of contamination to any of the testing personnel.

As the cartridge can be made from any suitable plastic material, thecosts can be maintained at a minimum, while insuring safety to thosecarrying out such tests.

Thus, there has been described with respect to one embodiment, anexample of the invention. Those skilled in the art will recognize yetother embodiments defined more particularly by the claims which follow.

What is claimed is:
 1. A disposable cartridge for measuring . .the.!.properties of blood comprising:a waste compartment for receiving bloodsamples which have been subject to measuring; a platform supported onsaid waste compartment including first and second fluidiccouplings.Iadd., .Iaddend.which receive . .the.!. front tip.Iadd.s.Iaddend.of first and second syringes which contain blood samples, ..connecting.!. .Iadd.wherein said fluidic couplings connect.Iaddend.said platform and syringes together. ., forming.!. .Iadd.toform .Iaddend. a leak-proof assembly, said fluidic couplings providing apressurizing fluid to said syringes and .Iadd.each .Iaddend.having anoutlet for delivering pressurized blood; .Iadd.first .Iaddend.guidemeans for supporting said syringes in alignment with said fluidiccouplings; first and second blood-carrying tubes mounted along a routingpath on a surface, connected to each of said outlets; a punchingmechanism comprising: a ram operated punching needle, said needle beingpositioned during a punching operation by a .Iadd.second .Iaddend.guide.Iadd.means .Iaddend.to punch an opening in said first blood carryingtube, permitting blood to exit through said opening; a first domedchamber receiving . .the.!. .Iadd.an .Iaddend.end of said firstblood-carrying tube, and receiving a .Iadd.first .Iaddend.pressurizingfluid from a .Iadd.first .Iaddend.source of pressurizing fluid ..for.!..Iadd., said receipt of said first pressurizing fluid.Iaddend.displacing air through a restricted orifice, . .and for.!..Iadd.said first source of pressurizing fluid .Iaddend.providing apressure transducer connection which measures changes in blood pressureoccurring during a flow of blood through said first blood-carrying tubeinto said first domed chamber, .Iadd.said flow of blood.Iaddend.displacing .Iadd.first .Iaddend.pressurizing fluid through saidrestrictive orifice into said waste compartment; and a second domedchamber receiving . .the.!. .Iadd.a .Iaddend.distal end of said secondblood carrying tube, and receiving a .Iadd.second .Iaddend.pressurizingfluid . .for.!. .Iadd.from a second source of pressurizing fluid saidreceipt of said second pressurizing fluid .Iaddend.displacing airthrough a restricted orifice in said second domed chamber, . .as wellas.!. .Iadd.said second source of pressurizing fluid .Iaddend.providinga connection to a pressure transducer for measuring changes in bloodpressure in said second blood-carrying tube from blood flowing throughsaid .Iadd.second .Iaddend.domed chamber.Iadd., said blood flow.Iaddend.displacing .Iadd.said second .Iaddend.pressurizing fluidthrough said restrictive orifice into said waste compartment.
 2. Thedisposable cartridge of claim 1 wherein said second blood-carrying tubecontains a platelet-induced body.
 3. The disposable cartridge of claim 1further comprising a vertically extending conduit connected to saidfluidic couplings which is received in said syringes, and supplies saidpressurizing fluid to said syringes.
 4. The disposable cartridges ofclaim 3 wherein said guide means position said syringes to be tangentialto a rear edge of said cartridge so that said syringes can be locatedagainst a common heating surface.
 5. The disposable cartridge of claim 1further comprising a tapered chamber having an axis aligned with saidpunching needle, said chamber tapered to receive an optical sensor fordetecting blood exiting from a punched hole in said first blood-carryingtube.
 6. The disposable cartridge of claim 5 wherein said taperedchamber includes an inlet for receiving a saline solution which washesblood from said hole punched in said first blood-carrying tube.
 7. Thedisposable cartridge of claim 1 wherein each of said first and secondblood-carrying tubes .Iadd.are supported .Iaddend.in a common plane topermit said tubes to be heated by a heating surface.
 8. An apparatus formeasuring the properties of blood comprising:a disposable cartridgeincluding first and second supports for vertically supporting twoblood-filled syringes, in first and second fluidic couplings forming asealed assembly therewith, said couplings having inlets for receiving apressurized fluid, and outlets for supplying blood . .and.!..Iadd., andsaid disposable cartridge further including .Iaddend.first and secondtesting channels for carrying blood from said outlets, and a wastereceptacle for receiving tested blood from said first and second testingchannels; and, a test stand for receiving said cartridge, said teststand having a heater for maintaining said blood-filled syringes at aconstant temperature, and including means for maintaining plungersassociated with said syringes in a fixed position when said disposablecartridge is receiving a pressurizing fluid, and a ram which operates apunching needle at a constant speed for punching a hole having a precisediameter in one of said testing channels.
 9. The apparatus of claim 8wherein said test stand further comprises a second heater formaintaining said first and second testing channels at a constanttemperature.
 10. The apparatus of claim 9 further comprising an opticalsensor support for maintaining an optical sensor positioned with respectto a bleeding chamber in one of said testing channels.
 11. The apparatusof claim 9, wherein said test stand further provides a connectionbetween a bleeding chamber centrally positioned with respect to said ..channel hole.!. .Iadd.punching needle .Iaddend.and a source of salinesolution.
 12. The apparatus of claim 8, wherein said test stand includesa source of pressurizing fluid coupled to said fluidic coupling inletswhen said cartridge is received in said test stand.
 13. The apparatus ofclaim 12, wherein said test stand includes first and second pressuretransducers which measure the blood pressure in said first and secondtesting chambers.
 14. A disposable cartridge for measuring physicalproperties of blood comprising:a waste compartment supporting aplatform, said platform having at least one fluidic coupling, and havinga guide for positioning at least one syringe holding a blood sample intosaid fluidic coupling which forms a sealed assembly . .therewith.!..Iadd.with said syringe.Iaddend.; at least one testing station.Iadd.,.Iaddend.located on said platform.Iadd., .Iaddend.for subjecting bloodflowing from said syringe to a testing condition, and connected .Iadd.tosaid waste compartment .Iaddend.to discharge tested blood in .Iadd.to.Iaddend.said waste compartment; and conduit means connecting said atleast one syringe to said testing station.
 15. A disposable cartridgeaccording to claim 14, wherein said testing station comprises means forcreating a precise opening in said conduit means to simulate bleeding.16. A disposable cartridge according to claim 14 further comprising asecond syringe having a blood sample.Iadd., said second syringe.Iaddend.forming a sealed assembly with said cartridge.Iadd.,.Iaddend.and a second testing station which includes a flow channelconnected to said second syringe having a blood sample . .whichincludes.!..Iadd., said flow channel including .Iaddend.a blood plateletactivating substance.
 17. The disposable . .apparatus.!. .Iadd.cartridge.Iaddend.of claim 14 further comprising a conduit extending through saidfluidic coupling along an axis of said syringe, and connected to receivea pressurizing media.
 18. The disposable cartridge of claim 14, whereinsaid test station further comprises a columnar pressure chamber having avolume of fluid immiscible with blood which is displaced by said blood,and which is connectable to a pressure transducer for monitoringpressure resulting from blood flowing into said columnar pressurechamber.
 19. The disposable cartridge of claim 14 wherein said testingstation includes means for introducing a shear force to blood flowing insaid channel, thereby activating blood platelets.